This application claims priority on Finnish Application No. 20000619, Filed Mar. 16, 2000, the disclosure of which is incorporated by reference herein.
Not applicable.
The invention concerns a roll provided with a continuous tubular shell of a composite material. Due to the advantageous characteristics of the material of a composite roll, such as elastic modulus and density, the composite roll can be dimensioned so that it may be bent into the desired curvature by a moderate moment and so that it will function either at a sub-critical speed, that is, below the lowest resonance frequency, or in between resonance frequencies. If it is desired to bend a steel roll into the required curvature without bringing about excessive tensions, the roll diameter must be very small. Hereby one or more critical roll speeds must unavoidably be exceeded.
With a steel roll, the bending moment needed for bending is also considerably higher than with a composite roll, whereby the bearing forces of the steel roll are also considerably higher than with a composite roll.
The applicant""s WO Publication 99/09329 presents a roll that can be bent for a web-like material. The roll includes a continuous tubular roll shell of a composite material as well as axle journals connected to either end of the roll shell. The axle journals are attached with at least one support point to a mounting flange structure mounted to the machine frame. In addition, the roll includes a bending mechanism, which is used for bending the axle journals and that way the roll shell into the shape of an arc, and a control device, which is used for controlling the angular position of the roll arc.
The solution according to the invention forms a simple alternative in relation to the solutions presented in the applicant""s above-mentioned WO publication.
In the roll according to the invention there is a continuous tubular roll shell of a composite material. At both ends of the roll shell there are axle journals rotating together with the roll shell. The axle journals are supported on a supporting element surrounding the axle journal by at least two bearing elements located at a distance from each other in the roll axis direction. The supporting element again is supported on to the machine frame structures through one support point. The first bearing element is supported on to the supporting element through a bending mechanism, by which the first bearing element can be moved in the radial direction as a pivot point is formed at the second bearing element, whereby a bending moment is applied to the roll shell. Thus, the roll structure is quite simple and it needs little maintenance. Owing to its simple structure, the roll is easy to manufacture and its costs are advantageous. In addition, the simple structure facilitates maintenance of the roll.
The roll according to the invention may be used e.g. as a spreader roll in a paper or board machine.
In the following, the invention will be described with reference to the figures shown in the appended drawings, but the intention is not to restrict the invention solely to the details of these figures.
Further objects, features and advantages of the invention will be apparent from the following detailed description when taken in conjunction with the accompanying drawings.